If there is a possibility that they might run on different computers then you need
a serverside solution.
don't know ColdFusion... You should post that query in the appropriate forum
As for the server listener, I've been playing around with dynamic script injection for something very similar... I came up with the following to get a simple update from the server to tell the page it needs to refresh, its not AJAX, but I need it to run on a local machine, so this gets around the cross domain scripting issues:
window.setInterval("document.getElementById('loadarea').src = 'http://www.mysite.com/update.js?nocash=' + Math.random()*500;",60000);
I just don't know how practical it is (or how unsecure it might be)